Physiology Flashcards
1
Q
What are the 3 classes of Hormones based on their chemical actions?
A
- Amino Acid Derivatives
- Peptides
3.Steroids
2
Q
Fill in the blanks. “Steroids are derived from _______.”
A
Cholesterol
3
Q
What are the 2 classes of Hormones based on their molecular mechanism?
A
1.Cell surface
2. Intra-cellular
4
Q
Where is Epinephrine secreted from?
A
The Adrenal Medulla
5
Q
Give examples of hormones that act on the cell surface?
A
Epinephrine , Glucagon ,
Insulin
6
Q
Fill in the blanks . “ Thyroid hormones are ________.”
A
Amino acid derivatives
7
Q
Where is the site for the Primary action of epinephrine?
A
Muscles
8
Q
Fill in the blanks. “ Epinephrine stimulates hydrolysis of _________ to _________ in adipocytes .”
A
It stimulates the hydrolysis of Triglycerides to Free Fatty Acids
9
Q
Which hormone is produced in a hypoglycaemic state?
A
Hyperglycaemic glycogenolytic hormone.
10
Q
What is the inactive form of Pancreatic polypeptide hormone?
A
Proglucagon
11
Q
True or False? Glucagon has no effect on muscle.
A
TRUE!!
12
Q
Fill in the blanks. “ Glucagon acts via ______.”
A
Andenyl cyclase
13
Q
Give examples of hormones that act intracellularly.
A
Lipid in nature ( steroids) , Thyroid Hormones
14
Q
Into what structures does the Hypothalamus release secretions into?
A
The median eminence,Posterior pituitary & Spinal cord
15
Q
Which Hypothalamic nuclei results in the secretion of Anti-diuretic hormone & Oxytocin?
A
Supra-optic nuclei
16
Q
What is the function of the Supra-chiasmatic nuclei?
A
It controls the circadian rhythm regulation & pineal gland function
17
Q
Which Hypothalamic Nuclei is responsible for the secretion of dopamine , growth - hormone releasing hormone & Gonadotrophin ?
A
Arcuate nuclei
18
Q
Fill in the blanks. “The Anterior Hypothalamic Nuclei mediates ________________ via ____________ and destruction leads to ___________.”
A
The Anterior Hypothalamic nuclei mediates HEAT DISSIPATION via PARASYMPATHETICS and destruction leads to HYPERTHERMIA.
19
Q
Fill in the blanks .” The Posterior Hypothalamic Nuclei mediates ___________ via __________ and destruction leads to ___________.”
A
The Posterior Hypothalamic nuclei mediates HEAT CONSERVATION via SYMPATHETICS and destruction leads to HYPOTHERMIA.
20
Q
What substances are secreted by the Paraventricular hypothalamic nuclei?
A
ADH
Corticotropin - releasing hormone
Oxytocin & Thyrotropin releasing hormone
21
Q
True or False? The lateral hypothalamic nuclei mediates satiety ,destruction leads to Hyperphagia and it is stimulated by Leptin.
A
FALSE!! The Ventromedial hypothalamic nuclei does this.
22
Q
Fill in the blanks.” The lateral hypothalamic nuclei mediates __________, destruction leads to ________ and it is _______ by Leptin .
A
The lateral hypothalamic nuclei mediates HUNGER , destruction leads to ANNOREXIA and it is INHIBITED by Leptin.
23
Q
Fill in the blanks. “ Neurosecretory neurons are _______, _______ secretory cells.
A
Glandular, Unmyelinated
24
Q
Where are Magnocellular (large) endocrine neurons located?
A
They are located in the paraventricular & supraoptic nuclei.
25
Where are Parvicellular (small) neurosecretory neurons located?
* The medial basal region,
* The arcuate& tuberal nuclei
* The periventricular region * The preoptic, paraventricular & suprachiasmatic nuclei
26
Fill in the blanks . " The Magnocellular (large) endocrine neurons Release secretions into the circulation by way of the ________."
Posterior pituitary
27
What controls the functions of Magnocellular secretions?
Cholinergic and Noradrenergic neurotransmitters
28
The Magnocellular neurons release what substances ?
ADH (Vasopressin) & Oxytocin
29
Fill in the blanks. " ________ stimulates the release of ADH and oxytocin by the Magnocellular neurons. "
Acetylcholine (Ach)
30
Fill in the blanks. " ________ inhibits the release of ADH and oxytocin by the Magnocellular neurons. "
Norepinephrine
31
True or False? Parvicellular Neurons are innervated by monoaminergic neurons (norepinephrine, dopamine, serotonin) which modulate the hypothalamic release of the hypophysiotropic hormones.
TRUE!!
32
Which substance is found as an intermediator for all steroid-secreting cells?
Progesterone
33
What is Progesterone produced by?
It is produced by Corpus Luteum and Placenta
34
What are the three forms of Estrogens?
Estrone (E1)
Estradiol (E2)
Estriol (E3)
35
Which forms of Estrogens are produced by the Ovaries?
Estrone (E1) & Estradiol (E2)
36
Which forms of Estrogens are produced by the Placenta?
Estrone (E1), Estradiol (E2)& Estriol (E3)
37
What are the metabolic effects of Estrogen?
Increase Lipogenesis Increase Protein synthesis
Maturation of bones
X growth (post puberty)
38
What effect does Estrogen have on the Cardiovascular System?
Increase in HDL
Increase in Platelet aggregation
Decrease in CT " Cutting time"
39
Fill in the blanks." Androgens are produced by ________."
Leydig cells
40
What is the Active metabolite of Androgens?
5α - dihydrotestosterone
41
Which Adrenocortical hormone is a steroid responsible for different concentration of energy/electrolyte?
Mineralocorticocoid
42
Which Adrenocortical hormones is responsible for sugar concentration and has anti-inflammatory properties?
Glucocorticoid
43
Aldosterone is produced by?
The Glomerulosa Zone
44
Where is the site that Aldosterone acts on?
Distal Convoluted tubules
45
What is Cortisol produced by?
Produced by Fasciculata reticularis zone ( Inner cortical region of the adrenal gland)
46
True or False? Glucocorticoids causes and INCREASE in blood sugar and liver glycogen deposit .
TRUE!!
47
The actions of cortisol interferes with which normal cellular processes?
Inflammation
Wound healing
Growth
48
True or False? Cortisol can be used in as palliative agents in the treatment of Asthma & Allergies .
TRUE!!
49
Which neurons release their product into the capillaries of the median emminence?
Parvicellular Neurons
50
Which hormone has a single chain of 41 amino acids?
Corticotrophin -releasing hormone.
51
Which hormone has a peptide of three amino acids?
Thyrotropin-releasing hormone.
52
What are the features of the Endocrine system?
* Slow speed of response
* Information conveyed by hormones
* Self-regulating
53
Where are Peptide hormones synthesised and released?
They are synthesised in the Rough ER , stored in vesicles and released by exocytosis.
54
Where are Steroid hormones synthesised?
In the Smooth ER
55
Secretions of Hormones within approximately one hour is described as?
Circhoral
56
Secretions secreted within more than an hour but less than 24 hours can be described as ?
Ultradian
57
Secretions of hormones done within approximately 24 hours is called?
Circadian or diurnal
58
Secretions of hormones for a period longer than one day considered?
Infra-radian
59
What are examples of circhoral hormones?
Pulsatile secretion of renin, oestradiol & progesterone
60
How are insoluble hormones transported?
By albumin and globulin
61
What are examples of Autocrines?
Eicosanoids ( prostaglandins, thromboxanes, prostacyclins,leukotrienes)
62
What are examples of Paracrines?
Somatostatin , Histamine, Eicosanoids
63
Where are receptors for the water soluble hormones found?
On the surface of the target cell , on the plasma membrane.
64
Where are receptors for the lipid soluble hormones found?
They are found in the nucleus ( and sometimes in the cytoplasm ) of the target cell.
65
The lipid soluble hormone diffuses into the cell and binds to the receptor . After,where does the receptor-hormone complex binds to?
It binds to specific DNA sequences called response elements.
66
What are examples of Anterior pituitary hormones?
Human Growth hormone
TSH
ACTH
FSH
LH
Prolactin
MSH ( Melanocyte stimulating hormone)
67
What are examples of lipid-soluble hormones?
Aldosterone
Calcitriol
Testosterone
Estrogen
Progesterone
T3 & T4
68
Fill in the blanks. "Hormonally induced negative regulation of receptors is referred to as _____________."
Homologous-desensitization.
69
What is Heterologous desensitization ?
Heterologous desensitization occurs when exposure of the cell to one agonist reduces the responsiveness of the cell to any other agonist that acts through a different receptor.
70
What is Down regulation?
Decrease in target cell receptors when excess hormone is present.
71
What is Up regulation?
Increase in target cell receptors when there is hormone deficiency
72
What is Metabolic Clearance rate?
Metabolic clearance rate is the volume of plasma cleared of the hormone per unit of time.
73
What is the half life for Amine hormones?
2-3 min
74
What is the half life for Steroid hormones?
4-120 min
75
How can one determine the measurement of hormones?
* Radioimmunoassay
* Chemiluminescence
* Enzymatic detection (ELISA) for radioactivity
* Mass spectrometry
76
Hypersecretion of Thyroxine can cause what disease?
Grave's disease
77
Hyposecretion of Thyroxine can cause what disease?
Goiter
78
Tertiary Endocrine diseases has occurs where?
At the level of the hypothalamus
79
What are the secretory cells for Acidophils?
Somatotrope
Lactotrope
80
What are the secretory cells for Basophils?
Corticotrope
Thyrotrope
Gonadotrope
81
Somatotropes produce what hormone?
Human growth hormone (hGH)
82
Lactrotropes produce what hormone?
Prolactin (PRL)
83
Corticotropes produce what hormone?
Adrenocorticotropin (ACTH)
84
Thyrotropes produce what hormone?
Thyroid-Stimulating hormone.
85
Gonadotrope prodcuces what hormone?
Luteinizing hormone (LH) & Follicle stimulating hormone (FSH)
86
Adrenocorticotropic hormone (ACTH) is stimulated by what hormone and from where?
It is stimulated by Cortico- Releasing hormone(CRH) in the hypothalamus.
87
What substance potentiates the release of Adrenocorticotropic hormone?
Vasopressin
87
Fill in the blanks. " Thyroid stimulating hormone is stimulated by _______."
Thyrotropin-releasing hormone (TRH)
88
What inhibits Thyroid stimulating hormone?
T3 (Triiodothyronine) ,T4 (Thyroxine) & Stress.
89
True or False? TSH is low in hypothyroidism of pituitary origin, but elevated in hypothyroidism of thyroidal origin.
TRUE!!
90
FSH is stimulated by ?
Gonadotropin-releasing hormone (GnRH) & Activin.
91
Fill in the blanks. "FSH secretion is inhibited by _______."
Inhibin
92
What are the consequences of a Hypophysectomy?
* Growth retardation
* Hypothyroidism
* Atrophy of the adrenal cortex
* Infertility
93
Which hormone is a potent inhibitor of Growth hormone?
Somatostatin
94
What is the circulating half life of Growth hormone?
20 minutes
95
What are the actions of Growth hormone?
* Promote growth of soft tissues, cartilages and bones.
* Growth-promoting action mediated by IGF-1.
* Increase blood glucose.
* Increase protein synthesis.
* Increase free fatty acid levels
96
Where produces the highest concentration of Gherlin?
The fundus of the stomach
97
True or False? Grhelin decreases growth hormone production after a meal.
FALSE!! It increases growth hormone production.
98
A lack of Growth Hormone receptors results in ?
Laron dwarfism
99
What are the symptoms of Acregomegaly?
1. Large Nose & Jaw
2. Galactorrohea
3. Sexual dysfunction
4. Cardiomegaly
5. Hypertrophy of sweat & sebaceous glands
100
What is the formula to calculate Eunucnoid proportions?
2C/ (A+B) >1.0
The ratio of a full arm span (C x 2 ) to full body height (A+B) is greater than 1.0
101
What are the different Eunucnoid Body Shapes?
* Congenital/ Early-life - Broad pelvis.
* Pre-pubertal - Broad pelvis & narrow shoulders.
* Post-pubertal - Narrow pelvis & narrow shoulders.
102
Which hormone has a 199 amino acid single chain?
Prolactin
103
True or False? Lactotropes are not apart of an endocrine axis.
TRUE!!
104
Fill in the blanks. " Production of Prolactin is under inhibitory control by the hypothalamus via______."
Dopamine
105
What are factors that stimulate Prolactin?
– sleep
– exercise
– stress
– nipple stimulation
– pregnancy
106
What are Prolactin releasing factors?
* Thyrotropin-releasing hormone (TRH)
* Angiotensin II
* AVP
* SubstanceP
* Beta-endorphin
106
What inhibits Prolactin release?
* Prolactin-inhibiting factor.
* Serotonin antagonists & dopamine agonists block secretion of prolactin.
107
Which type of drugs can stimulate Prolactin secretion?
* Dopamine antagonists (phenothiazine & tranquilizers)
* Adrenergic blockers
* Serotonin agonists
108
What is the normal prolactin levels in males?
2 – 18 ng/ml
109
What is the normal prolactin levels in non-pregnant females?
2 – 29 ng/ml
110
What is Homonymous hemianopsia (or hemianopia)?
This is a field loss deficit in the same halves of the visual field of each eye, often resulting from cerebrovascular injury or tumor.
111
What is a significant diagnostic indication of a Hypothalamic disease?
Diabetes insipidus (due to vasopressin (AVP) deficiency)
112
Which nucleus controls Autonomic and Endocrine function?
Paraventricular nucleus
113
Which neurons release secretions into the portal vasculature to stimulate or inhibit secretions from the anterior pituitary?
Parvicellular (small) neurosecretory neurons
114
True or False? Sleep, pain, exercise, stress and morphine induce ADH release.
TRUE!!
115
What substance inhibits ADH release?
Alcohol
116
What is the amount of Iodine needed daily to maintain normal thyroid
function in adults?
120-150 μg
117
Fill in the blanks. "The transport of iodide into follicular cells is dependent upon a __________."
Na+/I- cotransport system
118
Where does oxidation of Iodide take place?
Occurs in follicular cells
119
What are the three types of proteins thyroid hormones are bound to?
a. Thyroxine binding globulin ... 80%
b. Thyroxine binding pre-albumin ... 10%
c. Plasma albumin (serum albumin) ... 10%
120
What is the duration for sufficient storage of T3 & T4 in the Thyroid glands?
2-3 months
121
What is the name of the transporter that binds thyroglobulin thereby facilitating the secretion of T4 and T3 into the blood stream?
Megalin
122
Which Thyroid hormone is considered active ?
3,5,3’- T3 Triiodothyronine (10%)
123
Where is Thyroxine-binding globulin (TBG) synthesized?
In the Liver
124
What are examples of Endogenous & Exogenous agents that suppress Thyrotropin secretion?
* Thyroid hormones and analogues
* Dopamine and dopamine agonists
* Somatostatin and somatostatin analogues
* Dobutamine
* Glucocorticoids (acute, high-dose)
* Interleukin – 1, Interleukin-6
* Tumor necrosis factor
* Bexarotene (retinoid X receptor agonist)
*Phenytoin
125
Which substance stimulates proopiomelanocortin (POMC) -secreting hormones?
Leptin
126
What are the main functions of Leptin?
* Tells the brain how much fat is stored.
*Decreases appetite and increases metabolism.
127
Where is Thyrotropin - releasing hormone produced from?
Hypothalamic paraventricular nucleus (PVN
128
Which hormones involve the suppression of neurons in the arcuate nucleus that release Neuropeptide Y (NPY) and Agouti-related protein (AgRP)?
Leptin & Insulin
129
Which enzyme inactivates both T4 and T3 is lower whenever there is iodine restriction?
D3 ( Type 3 deiodinase)
130
What are the effects of Thyroid hormone on the Cardiovascular system?
* Increased Cardiac output (T3)
* Increased resting HR, SV
* Positive chronotropic and inotropic effects
* Positive lusitropic effect (shortened diastolic relaxation time)
* Modest increase in SBP and decrease in DBP.
131
True or False? Glycogen & creatinine phosphate are increased by excess T4 & T3
FALSE!! It is REDUCED.
132
What is the name of the enzyme that converts any cholesterol not used by cell to cholesterol ester?
Acyl CoA-cholesterol acyltransferase (ACAT)
133
What is the name of the enzyme that turns stored cholesterol back into free cholesterol by hydrolyzing the ester bond?
Cholesterol esterase / Cholesterol ester hydrolase (CEH)
134
What is the function of the enzyme 3-hydroxy-3 -methylglutaryl CoA reductase (HMG- CoA reductase)?
It is involved in the conversion of acetate to cholesterol
135
Where does the beginning of steroid synthesis take place?
In the mitochondria
136
What is the name of the protein that is necessary for the transport of cholesterol from the outer mitochondrial membrane to the inner mitochondrial membrane?
Steroidogenic acute regulatory protein (StAR protein)
137
What is the name of the enzyme attached to the inner mitochondrial membrane that converts Cholesterol to Pregnenolon?
CYP 11A1
138
What is the name of the protein to which cortisol is bound to?
Corticosteroid-binding globulin [CBG] (also called TRANSCORTIN ),
139
Where is the predominant site of steroid inactivation ?
The liver by conjugation with glucuronic acid
140
What is the circulating half life of cortisol?
70 mins
141
Fill in the blanks. " Cortisol is reversible inactivated by conversion to _____."
Cortisone
142
What is the name of the enzyme that catalyses cortisone production ( inactivation of cortisol)?
11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2).
143
True or False? Cortisol levels are highest during the eraly morning ( dawn ) and lowest in the evening.
TRUE!!
144
What potentiates the action of CRH?
ADH
145
What is the name of the receptor to which ACTH binds to?
Melanocortin 2 receptor (MC2R)
146
What are the acute effects of ACTH ?
* Cholesterol is rapidly mobilized from lipid droplets by post-translational activation of cholesterol ester hydrolase and transported to the outer mitochondrial
membrane.
*Increase in StAR protein gene expression and activates StAR protein through protein kinase A (PKA)-dependent phosphorylation
( Over a few minutes)
147
What are the chronic effects of ACTH ?
* These effects involve increasing transcription of the genes encoding the steroidogenic enzymes and their coenzymes.
*ACTH also increases expression of the LDL receptor and scavenger receptor BI (SR-BI; the HDL receptor).
( Occurs over several hours)
148
What are the trophic effects of ACTH ?
They act on the zona fasciculata and zona reticularis over weeks and months.
149
Fill in the blanks. " ____________ inhibits both POMC gene expression at the corticotropes and pro-CRH gene expression at the hypothalamus. "
Cortisol
150
What are the Metabolic actions of cortisol?
* Increase Gluconeogenesis
* Inhibits proteogenesis
* Stimulate proteolysis
* Increase Protein breakdown
* Increase Amino acid release
* Increase Fatty acid release
151
What is the Zona glomerulosa regulated by?
* The renin- angiotensin system
* plasma [K+]
* Atrial natriuretic peptide (ANP).
* ACTH (minimal)
152
What enzyme is NOT expressed by the zona glomerolosa?
CYP17 ( 17- alpha hydroxylse)
153
What reactions in the formation of aldosterone is catalysed by the enzyme aldosterone synthase ( coded by CYP11B2) ?
* 11-hydroxylation of DOC to form corticosterone,
* 18-hydroxylation to form 18 - hydroxycorticosterone,
* 18-oxidation to form aldosterone
154
What is the name given to the protein to which Aldosterone is bound to?
Albumin and corticosteroid-binding protein.
155
What is the half-life of Aldosterone?
20 minutes
156
What is the name of the receptor to which Aldosterone binds to?
Mineralocorticoid receptor [MR])
157
Where is the site, synthesis and storage of renin?
Juxtaglomerular cells, also known as granular cells
158
Angiotensininogen is produced by the ?
Liver
159
Where is Angiotensin I converted to Angiotensin II?
In the lungs and renal epithelial cells
160
What is the enzyme that converts Angiotensin I to Angiotensin II?
Angiotensin-converting enzyme (ACE)
161
Where is the Angiotensin-converting enzyme (ACE) enzyme located?
On the surface of vascular endothelial cells
162
When does the zona reticularis start to appear after birth?
At about 5 years of age.
163
What are the main products of the Zona reticularis?
Androgens & Dehydroepiandrosterone (DHEA)
164
The enzyme 3β-Hydroxysteroid dehydrogenase (3β-HSD) is expressed in very low levels in which layer of the adrenal cortex?
Zona reticularis
165
What is the name of the enzyme that converts DHEA to DHEAS?
DHEA sulfotransferase (SULT2A1 gene),
166
Fill in the blanks. " Most most active sex steroids are produced primarily from __________."
Peripheral conversion of DHEAS and androstenedione."
167
Fill in the blanks. "DHEAS can be converted back to DHEA by _______."
Peripheral sulfatases
168
What is the half life of DHEA?
15-30 minutes
169
What is the half life of DHEAS?
7-10 hours
170
True or False? DHEA binds to albumin and other globulins in blood with LOW affinity while DHEAS binds to albumin with very HIGH affinity.
TRUE!!
171
What is the most abundant circulating hormone in young adults?
DHEAS
172
What is the primary regulator of the zona reticularis?
ACTH
173
True or False? Both DHEA and androstenedione display the same diurnal rhythm as cortisol (DHEAS does not because of its long cir- culating half-life).
TRUE !!
174
True or False? Cortisol inhibits phospholipase A2?
TRUE!!
175
True or False? Cortisol increases bone reabsorption.
TRUE!!
176
True or False? Glucoocrorticoids INHIBIT inflammation.
TRUE!!
It inhibits -
Arachodonic acid
Platelet activating factor
Tumour Necrosis factor
Interleukin -1
Plasminogen activator.
177
Where is phosphate metabolised?
In the bone
178
What is the major anion in bones and teeth?
Phosphate
179
What are the functions of Phosphate?
Integral part of glycolytic compounds
Regulation of blood and urine pH
Part of energy transfer compounds
Major anion in bone and teeth
180
What are the actions of Amylin?
Inhibits the secretion of glucagon
Slows the emptying of stomach
Sends a satiety signal to the brain
181
What produces Glucagon-like peptide 1 (GLP-1)?
L cells
182
What are the two enzymes involved in the degradation of catecholamines?
Monoamine oxidase (MAO)
Catechol-O-methyltransferase (COMT)
183
